TM 9-4120-378-14
Table 5-1. Direct Support Troubleshooting - Continued
Malfunction
Test or Inspection
Corrective Action
LOW HEAT OR NO HEAT
7.
Check heater wiring and control circuit for loose connections or broken wires.
Step 1.
a. Tighten loose connections.
b. Replace or repair broken wires. (Refer to paragraphs 4.35, 4.24 and 4.26.)
Check continuity of Mode Selector switch and Temperature Selector switch. (Refer
Step 2.
Disconnect and remove heater elements, and apply 115-volt AC power to check for
Step 3.
open circuit in element. Element should heat.
Replace faulty heating elements. (Refer to paragraph 4.35.)
Check continuity of HIGH pressure cutout switch at room temperature. Continuity
Step 4.
should exist. (Refer to paragraph 5.21.)
a. If continuity does not exist, press reset button and recheck. (Refer to
b. Replace faulty switch.
Disconnect heater relay. Apply 24-28 volts DC to actuate relay and check
Step 5.
continuity at secondary terminals. Continuity should exist. (Refer to paragraph
4.25.)
Replace faulty relay. (Refer to paragraph 4.25.)
Check operation of evaporator fan and motor. (Refer to paragraphs 4.32 and
Step 6.
4.33.)
Repair or replace faulty fan or motor. (Refer to paragraphs 4.32 and 4.33.)
5-6
